81891445248 has 240 divisors, whose sum is σ = 243861422376. Its totient is φ = 26435911680.

The previous prime is 81891445201. The next prime is 81891445291. The reversal of 81891445248 is 84254419818.

81891445248 is a `hidden beast` number, since 8 + 189 + 1 + 4 + 452 + 4 + 8 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 81266045184 + 625400064 = 285072^2 + 25008^2 .

It is a junction number, because it is equal to n+sod(n) for n = 81891445194 and 81891445203.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 41088540 + ... + 41090532.

Almost surely, 2^81891445248 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81891445248, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (121930711188).

81891445248 is an abundant number, since it is smaller than the sum of its proper divisors (161969977128).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81891445248 is a wasteful number, since it uses less digits than its factorization.

81891445248 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2295 (or 2276 counting only the distinct ones).

The product of its digits is 2949120, while the sum is 54.

The spelling of 81891445248 in words is "eighty-one billion, eight hundred ninety-one million, four hundred forty-five thousand, two hundred forty-eight".